title: In vivo expansion of CD4+Foxp3+ regulatory T cells mediated by GITR molecules.
abstract: CD4(+)Foxp3(+) regulatory T cells (Treg cells) play an important role in maintaining self-tolerance as suppressive/regulatory CD4 T cells. In vitro analyses have revealed the characteristics of Treg cells, that is, hyporesponsiveness when stimulated via TCR in the presence of splenic APC. In this study, we report a new mAb, G3c, which can induce the expansion of Treg cells stimulated with anti-CD3 Ab along with splenic APC, the culture conditions in which Treg cells exhibit hyporesponsiveness. Surprisingly, G3c mAb recognized glucocorticoid-induced TNFR family-related proteins (GITR). G3c mAb had stronger co-stimulatory activity for both Treg cells and responder T cells than another anti-GITR Ab (DTA1) in vitro. The in vivo administration of G3c increased the number of Treg cells and had less effect in inducing anti-tumor immunity in normal mice, although G3c had some anti-tumor effect on non-Treg cells in the absence of Treg cells in vivo, in contrast to the anti-tumor therapeutic effect of DTA1 in normal mice. Therefore, we need to know that the manipulation of immune responses with the use of anti-GITR Abs results from a balance between co-stimulatory effects on Treg cells and on responder cells, and we must aim at a narrow window leading to the therapeutic effects.
authors.affiliation: Section of Immunology, Department of Mechanism of Aging, National Institute for Longevity Sciences, National Center for Geriatrics and Gerontology, Obu 474-8522, Japan.
authors.forename: Tomohisa
authors.initials: T
authors.lastname: Nishioka
authors.forename: Emi
authors.initials: E
authors.lastname: Nishida
authors.forename: Ryuji
authors.initials: R
authors.lastname: Iida
authors.forename: Akimichi
authors.initials: A
authors.lastname: Morita
authors.forename: Jun
authors.initials: J
authors.lastname: Shimizu
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D017252:CD3 Complex / Q000276:immunology; D015704:CD4 Antigens; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D017635:Clonal Anergy / Q000276:immunology; D000939:Epitopes; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D053450:Glucocorticoid-Induced TNFR-Related Protein; D008213:Lymphocyte Activation / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D051381:Rats; D017208:Rats, Wistar; D017475:Receptors, Nerve Growth Factor / Q000276:immunology*; D018124:Receptors, Tumor Necrosis Factor / Q000276:immunology*; D016176:T-Lymphocyte Subsets / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology* / Q000378:metabolism / Q000473:pathology
chemical_list: D000911:Antibodies, Monoclonal; D017252:CD3 Complex; D015704:CD4 Antigens; D000939:Epitopes; D051858:Forkhead Transcription Factors; C498833:Foxp3 protein, mouse; D053450:Glucocorticoid-Induced TNFR-Related Protein; D017475:Receptors, Nerve Growth Factor; D018124:Receptors, Tumor Necrosis Factor; C106544:Tnfrsf18 protein, mouse